package com.wenx.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;

/**
 * Created by wenx on 2019-10-10 17:29
 */
public class NIOSocketServer {

    private static final int BUF_SIZE=1024;
    private static final int PORT = 8081;
    private static final int TIMEOUT = 3000;

    public static void main(String[] args) {
        selector();
    }

    private static void selector() {
        Selector selector = null;
        ServerSocketChannel serverSocketChannel = null;
        try {
            selector = Selector.open();
            serverSocketChannel = ServerSocketChannel.open();
            serverSocketChannel.socket().bind(new InetSocketAddress(PORT));
            serverSocketChannel.configureBlocking(false);
            serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
            while (true) {
                if(selector.select(TIMEOUT) == 0) {
                    System.out.println("==");
                    continue;
                }
                Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
                while (iter.hasNext()) {
                    SelectionKey key = iter.next();
                    if(key.isAcceptable()){
                        handleAccept(key);
                    }
                    if(key.isReadable()){
                        handleRead(key);
                    }
                    if(key.isWritable() && key.isValid()){
                        handleWrite(key);
                    }
                    if(key.isConnectable()){
                        System.out.println("isConnectable = true");
                    }
                    iter.remove();
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if(selector != null) {
                    selector.close();
                }
                if(serverSocketChannel != null) {
                    serverSocketChannel.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private static void handleAccept(SelectionKey key) throws IOException{
        ServerSocketChannel ssChannel = (ServerSocketChannel)key.channel();
        //监听新进来的连接
        SocketChannel sc = ssChannel.accept();
        sc.configureBlocking(false);
        sc.register(key.selector(), SelectionKey.OP_READ, ByteBuffer.allocateDirect(BUF_SIZE));
    }

    private static void handleRead(SelectionKey key) throws IOException{
        SocketChannel sc = (SocketChannel)key.channel();
        ByteBuffer buf = (ByteBuffer)key.attachment();
        long bytesRead = sc.read(buf);
        while(bytesRead>0){
            buf.flip();
            while(buf.hasRemaining()){
                System.out.print((char)buf.get());
            }
            System.out.println();
            buf.clear();
            bytesRead = sc.read(buf);
        }
        if(bytesRead == -1){
            sc.close();
        }
    }

    private static void handleWrite(SelectionKey key) throws IOException{
        ByteBuffer buf = (ByteBuffer)key.attachment();
        buf.flip();
        SocketChannel sc = (SocketChannel) key.channel();
        while(buf.hasRemaining()){
            sc.write(buf);
        }
        buf.compact();
    }

}